Earlier today I was greeted with this message while performing a BOSH deployment for SHIELD:

Error 100: Unknown CPI error 'Unknown' with message 'AWS was not able to validate the provided access credentials'

I double checked the AWS Access and Secret permissions. I even deployed from my laptop a test deployment with the same keys with no issue. So the problem was not with the keys.

After digging around I found this article which pointed me to check the time on the BOSH Director. Why? The BOSH AWS CPI is using the AWS CLI to perform actions which leverage a token which is time sensitive.